Hi, I'd like to help you with your question.
Many clinicians are not trained well in personality disorders. And an anti social personality is very charming and manipulative and therefore hard to recognize and deal with. It is easy to believe what they say and even with training a therapist can be convinced to believe what they say. The therapist needs experience in order to deal with them.
To find a good therapist, make sure you interview them before you make an appointment. Ask about experience and you may want to consider someone who has been in practice for a while and also ask them if they have direct experience dealing with anti social personalities. Also, you may want to consider avoiding clinicians that are trained in CBT (Cognative Behavioral Therapy) only. CBT therapists are trained to recognize thought patterns and behaviors but they are not trained to look into motivations and underlying reasons for behavior. Therefore, someone with anti social behavior may look normal to them. You also may want to be sure you have someone who has certain training. Here is a list of Master Level and Ph.D therapists degrees and what they mean:
M.Ed- A Masters in Counselor education
M.S.W.- a Master's in Social Work
L.S.W.- the same as above, but Licensed
M.A.- a Master's in theories of psychology
MFT- Master's in Family and Marital therapy
Ph.D- a doctorate in Psychology
Psy.D- a doctorate in applied clinical psychology
You want a therapist who is trained in counseling. Social Workers are trained in family systems, M.A.'s in theory and MFT's in marital and family, which may work for you if they have experience with mental illness in families.
Here are some resources to help you find a therapist in your area:
http://www.therapistlocator.net/- for MFT's
You may also want to contact local universities and hospitals to see if they can provide referrals to therapists in the area who have experience with personality disorders and families.
I hope this helps. Please let me know if you have any further questions.